Yes, sorry I did not look closer... regex can match any finite language, so there are no data sets you can feed to R that cannot be matched. [1] You may find it hard to see the pattern, or you may want to build the pattern programmatically to alleviate tedium for yourself, but regexes are not the constraint.
http://www.cs.nuim.ie/~jpower/Courses/Previous/parsing/node18.html -- Sent from my phone. Please excuse my brevity. On September 4, 2016 10:41:45 PM PDT, Bert Gunter <bgunter.4...@gmail.com> wrote: >Well, he did provide an example, and... > > >> z <- c('TX.WT.CUT.mean','mg.tx.cv') > >> sub("^.+?\\.(.+)\\.[^.]+$","\\1",z) >[1] "WT.CUT" "tx" > > >## seems to do what was requested. > >Jeff would have to amplify on his initial statement however: do you >mean that separate patterns can always be combined via "|" ? Or >something deeper? > >Cheers, >Bert >Bert Gunter > >"The trouble with having an open mind is that people keep coming along >and sticking things into it." >-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > >On Sun, Sep 4, 2016 at 9:30 PM, Jeff Newmiller ><jdnew...@dcn.davis.ca.us> wrote: >> Your opening assertion is false. >> >> Provide a reproducible example and someone will demonstrate. >> -- >> Sent from my phone. Please excuse my brevity. >> >> On September 4, 2016 9:06:59 PM PDT, Jun Shen <jun.shen...@gmail.com> >wrote: >>>Dear list, >>> >>>I have a vector of strings that cannot be described by one pattern. >So >>>let's say I construct a vector of patterns in the same length as the >>>vector >>>of strings, can I do the element wise pattern recognition and string >>>substitution. >>> >>>For example, >>> >>>pattern1 <- "([^.]*)\\.([^.]*\\.[^.]*)\\.(.*)" >>>pattern2 <- "([^.]*)\\.([^.]*)\\.(.*)" >>> >>>patterns <- c(pattern1,pattern2) >>>strings <- c('TX.WT.CUT.mean','mg.tx.cv') >>> >>>Say I want to extract "WT.CUT" from the first string and "tx" from >the >>>second string. If I do >>> >>>sub(patterns, '\\2', strings), only the first pattern will be used. >>> >>>looping the patterns doesn't work the way I want. Appreciate any >>>comments. >>>Thanks. >>> >>>Jun >>> >>> [[alternative HTML version deleted]] >>> >>>______________________________________________ >>>R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>>https://stat.ethz.ch/mailman/listinfo/r-help >>>PLEASE do read the posting guide >>>http://www.R-project.org/posting-guide.html >>>and provide commented, minimal, self-contained, reproducible code. >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
